An improved add/drop multiplexer in which groups of working channel tributaries have associated groups of protection channel tributaries is provided. Traffic is added by receiving it from an external service, and transmitting it on a configured group of working channel tributaries unless a protection event has occurred requiring it to be transmitted on the associated group of protection channel tributaries. Traffic received from protection or working channel tributaries is either dropped at the multiplexer if addressed to it, or transmitted on tributaries of the same type, be it working or protection. If working channel tributaries for use in the transmission relate to a physical link which is down, then the traffic is transmitted on the associated group of protection channel tributaries. In this way, all the working channel tributaries can be shared among users, rather than having a dedicated working channel tributary for each user.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An add/drop multiplexer comprising: a plurality of service terminating units (STUs) each having an associated identifier operable to receive information units from external services and converting these into switching units containing a destination identifier, and to receive switching units having the associated identifier and combine them into information units and output them to the external services; a switching component having a first set of dedicated receive ports operable to receive working channel traffic, a first set of dedicated transmit ports operable to transmit working channel traffic, a second set of dedicated receive ports operable to receive protection channel traffic, a second set of dedicated transmit ports operable to transmit channel traffic, and an STU port for each STU operable to receive switching units from the respective STU and to send switching units to the respective STU; wherein switching units received by the switching component from the STUs are output through the first set of dedicated transmit ports unless a protection event has occurred affecting those ports in which case the switching units are output through the second set of dedicated transmit ports; and wherein the destination identifier of each switching unit received by the switching component from the first set of dedicated receive ports is examined by the switching component, and if the destination identifier is the same as the identifiers associated with one of said STUs, the switching unit is passed to the one of said STUs, and otherwise the switching unit is output through the first set of dedicated transmit ports unless a protection event has occurred effecting those ports in which case the switching unit is output through the second set of dedicated transmit ports.
2. A multiplexer according to claim 1 wherein: said first set of dedicated receive ports comprises a respective first subset of receive ports through which cells can be received from a first neighbour node, and a respective second subset of receive ports through which cells can be received from a second neighbour node; said second set of dedicated receive ports comprises a respective first subset of receive ports through which cells can be received from the first neighbour node, and a respective second subset of receive ports through which cells can be received from the second neighbour node; said first set of dedicated transmit ports comprises a respective first subset of transmit ports through which cells can be transmitted to the first neighbour node, and a respective second subset of transmit ports through which cells can be transmitted to the second neighbour node; said second set of dedicated transmit ports comprises a respective first subset of transmit ports through which cells can be transmitted to a first neighbour node, and a respective second subset of transmit ports through which cells can be transmitted to a second neighbour node.
3. A multiplexer according to claim 2 for connection to an incoming East-West fiber, an outgoing East-West fiber, an incoming West-East fiber and an outgoing West-East fiber, the ADM further comprising: a first fiber termination unit receive circuit connected to receive optical signals from the incoming West-East fiber, operable to convert these to electrical signals and to pass them to the first subset of the first set of dedicated receive ports and the first subset of the second set of dedicated receive ports; a second fiber termination unit receive circuit connected to receive optical signals from the incoming East-West fiber, operable to convert these to electrical signals and to pass them to the second subset of the first set of dedicated receive ports and the second subset of the second set of dedicated receive ports; a first fiber termination unit transmit circuit connected to receive electrical signals from the second subset of the first set of dedicated transmit ports and the second subset of the second set of dedicated transmit ports, operable to convert these to optical signals and to transmit them on the outgoing West-East fiber; a second fiber termination unit transmit circuit connected to receive electrical signals from the first subset of the first set of dedicated transmit ports and the first subset of the second set of dedicated transmit ports, operable to convert these to optical signals and to transmit them on the outgoing East-West fiber.
4. A multiplexer according to claim 3 wherein a first dedicated set of tributaries of said East-West fiber are connected to function as a first set of-working channels, a second dedicated set of tributaries of said East-West fiber are connected to function as a first set of protection channels, a first dedicated set of tributaries of said West-East fiber are connected to function as a second set of working channels, and a second dedicated set of tributaries of said West-East fiber are connected to function as a second set of protection channels.
5. A multiplexer according to claim 3 wherein a particular port for each switching unit is selected to be a next available port.
6. A bi-directional line switched ring comprising a plurality of ADMs according to claim 1 connected together by two fiber rings.
7. An ADM according to claim 1 wherein said STUs include at least one STU operable to handle a DS3 external service, each such STU comprising circuitry operable to convert DS3 packets into switching units having the STU's identifier and to output these to the switching component, and circuitry operable to convert switching units received from the switching component having the STU's identifier into DS3 packets and to output these to the external service.
8. An ADM according to claim 1 wherein said STUs include at least one STU operable to handle an IP external service, each such STU comprising circuitry operable to convert IP packets into switching units cells having the STU's identifier and to output these to the switching component, and circuitry operable to convert switching units received from the switching component having the STU's identifier into IP packets and to output these to the external service.
9. An ADM according to claim 1 wherein said STUs include at least one STU operable to handle an Ethernet external service, each such STU comprising circuitry operable to convert Ethernet packets into switching units having the STU's identifier and to output these to the switching component, and circuitry operable to convert switching units received from the switching component having the STU's identifier into Ethernet packets and to output these to the external service.
10. An ADM according to claim 1 wherein the switching component is an ATM (asynchronous transfer mode) switch, the switching units are ATM cells, and the STU identifiers are ATM identifiers.
11. An ADM according to claim 1 wherein the switching component decides whether to send a switching unit on working channel ports or protection channel ports.
12. An ADM according to claim 7 wherein the fiber termination units decide whether to send a switching unit on working channels or on protection channels.
13. A multiplexing method in a multiplexer comprising: providing a plurality of I/O ports to external services each having an address; providing at least one set of groups of tributaries, the set of groups of tributaries comprising: a) a first group of input working channel tributaries on a first physical link, a first group of output working channel tributaries on a second physical link; b) a first group of input protection channel tributaries on the second physical link and a first group of output protection channel tributaries on the first physical link; c) a second group of input working channel tributaries on a third physical link, a second group of output working channel tributaries on a fourth physical link; d) a second group of input protection channel tributaries on the fourth physical link and a second group of output protection channel tributaries on the third physical link; the second group of output protection channel tributaries being associated with the first group of input working channel tributaries, and the first group of output protection channel tributaries being associated with the second group of input working channel tributaries; configuring for each of said I/O ports a respective one of said groups of output working channel ports; for each set of groups: a) for traffic received on the first group of input working channel tributaries, dropping traffic addressed to one of said I/O ports, outputting traffic not addressed to any of said I/O ports on the first group of output working channel tributaries unless the second physical link is down in which case outputting the traffic on the second group of output protection channel tributaries; b) for traffic received on the second group of input working channel tributaries, dropping traffic addressed to one of said I/O ports, outputting traffic not addressed to any of said I/O ports on the second group of output working channel tributaries unless the fourth physical link is down in which case outputting the traffic on the first group of output protection channel tributaries; c) for traffic received on the first group of input protection channel tributaries, dropping traffic addressed to one of said I/O ports, outputting traffic not addressed to any of said I/O ports on the first group of output protection channel tributaries unless the second physical link is down in which case terminating the traffic; d) for traffic received on the second group of protection working channel tributaries, dropping traffic addressed to one of said I/O ports, outputting traffic not addressed to any of said I/O ports on the second group of output protection channel tributaries unless the fourth physical link is down in which case terminating the traffic; for each traffic unit received from the I/O ports, outputting it on a respective configured one of said groups of output working channel tributaries unless the physical link for the configured group is down in which case outputting the traffic on the group of protection channel tributaries associated with the configured group.
14. A method according to claim 13 wherein there is a single one of said sets of groups.
15. A method according to claim 13 wherein there are at least two of said sets of groups defined on the same four physical links, each group being configured to handle traffic for a certain group of said I/O ports.
16. A method according to claim 13 further comprising converting traffic formats of the external services to a first common traffic format handled by the physical links.
17. A method according to claim 16 wherein converting traffic formats of the external services to a common format handled by the physical links comprises converting traffic formats of the external services to a second common format appropriate for use internal to the multiplexer in determining which group of output tributaries to use, and after determining which group of output tributaries to use, converting the second common traffic format to the first common traffic format.
18. An asynchronous transfer mode (ATM) based add/drop multiplexer (ADM) comprising: a plurality of service terminating units (STUs) each having an associated ATM identifier operable to receive information units from external services and to convert these into ATM cells containing said associated ATM identifier, and to receive ATM cells having the associated ATM identifier and combine them into information units and output them to the external services; an ATM switch having a first set of dedicated receive ports operable to receive working channel traffic, a first set of dedicated transmit ports operable to transmit working channel traffic, a second set of dedicated receive ports operable to receive protection channel traffic, a second set of dedicated transmit ports operable to transmit channel traffic, and an STU port for each STU operable to receive cells from the STU and to send cells to the STU; wherein cells received by the ATM switch from the STUs are output through the first set of dedicated transmit ports unless a protection event has occurred effecting the first set of dedicated transmit ports in which case the cells arc output through the second set of dedicated transmit ports; and wherein the ATM identifier of each cell received by the ATM switch from the first set of dedicated receive ports is examined by the ATM switch, and if the ATM identifier is associated with one of said STUs, the cell is passed to the one of said STUs, and otherwise the cell is output through the first set of dedicated transmit ports unless a protection event has occurred effecting the first set of dedicated transmit ports in which case the cells are output through the second set of dedicated transmit ports.
19. An ADM according to claim 18 wherein: said first set of dedicated receive ports comprises a respective first subset of receive ports through which cells can be received from a first neighbour node, and a respective second subset of receive ports through which cells can be received from a second neighbour node; said second set of dedicated receive ports comprises a respective first subset of receive ports through which cells can be received from the first neighbour node, and a respective second subset of receive ports through which cells can be received from the second neighbour node; said first set of dedicated transmit ports comprises a respective first subset of transmit ports through which cells can be transmitted to the first neighbour node, and a respective second subset of transmit ports through which cells can be transmitted to the second neighbour node; said second set of dedicated transmit ports comprises a respective first subset of transmit ports through which cells can be transmitted to a first neighbour node, and a respective second subset of transmit ports through which cells can be transmitted to a second neighbour node.
20. An ADM according to claim 19 for connection to an East-West fiber and a West-East fiber, the ADM further comprising: a first fiber termination unit receive circuit connected to receive optical signals from the West-East fiber, operable to convert these to electrical signals and to pass them to the first subset of the first set of dedicated receive ports and the first subset of the second set of dedicated receive ports; a second fiber termination unit receive circuit connected to receive optical signals from the East-West fiber, operable to convert these to electrical signals and to pass them to the second subset of the first set of dedicated receive ports and the second subset of the second set of dedicated receive ports; a first fiber termination unit transmit circuit connected to receive electrical signals from the second subset of the first set of dedicated transmit ports and the second subset of the second set of dedicated transmit ports, operable to convert these to optical signals and to transmit them on the West-East fiber; a second fiber termination unit transmit circuit connected to receive electrical signals from the first subset of the first set of dedicated transmit ports and the first subset of the second set of dedicated transmit ports, operable to convert these to optical signals and to transmit them on the East-West fiber.
21. An ADM according to claim 18 wherein said STUs include at least one STU operable to handle a DS3 external service, each such STU comprising circuitry operable to convert DS3 packets into ATM cells having the STU's ATM identifier outputting these to the ATM switch, and circuitry operable to convert ATM cells received from the ATM switch having the STU's ATM identifier into DS 3 packets and to output these to the external service.
22. An ADM according to claim 18 wherein said STUs include at least one STU operable to handle an IP external service, each such STU comprising circuitry operable to convert IP packets into ATM cells having the STU's ATM identifier and to output these to the ATM switch, and circuitry operable to convert ATM cells received from the ATM switch having the STU's ATM identifier into IP packets and to output these to the external service.
23. An ADM according to claim 18 wherein said STUs include at least one STU operable to handling an Ethernet external service, each such STU comprising circuitry operable to convert Ethernet packets into ATM cells having the STU's ATM identifier and to output these to the ATM switch, and circuitry operable to convert ATM cells received from the ATM switch having the STU's ATM identifier into Ethernet packets and to output these to the external service.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
August 10, 1999
October 29, 2002
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